The present invention relates generally to spacecraft simulation, and more particularly to a complete spacecraft simulation system that is encapsulated and integrated within a single compact computer system.
The increasing size and complexity of various spacecraft and associated subsystems therefore have created a need for detailed validation and verification before deployment. Examples of spacecraft related subsystems requiring validation and verification include: (i) multiprocessor-based systems which can have complex software architectures; (ii) fault detection and response systems providing extended autonomous operation; (iii) multiple-articulated payloads and multibody control; (iv) precision payload pointing systems with multiple interacting elements; and (v) sophisticated ground software for automated spacecraft operations.
However, system-level ground testing to verify full system performance of a spacecraft can be costly and/or inadequate. Present implementations of hardware-in-the-loop systems to provide ground testing require expensive engineering models, as well as, special purpose interface hardware and harnessing to create a test environment whereby hardware or emulations thereof can be integrated with a high-fidelity, non-linear, real-time simulation and then instrumented to facilitate verification and validation testimony.
One prior emulation system is disclosed in U.S. Pat. No. 5,808,921. The ""921 patent is commonly assigned and has three common co-inventors with the present invention. In the ""921 patent, the emulation system requires special purpose interface hardware in the form of an additional computer system to provide a complete simulation of the tangent spacecraft as the system disclosed in the ""921 patent is only capable of emulating the spacecraft""s attitude control sub-system. Thus, in order to emulate other sub-systems, a separate computer system is required. The simulation system disclosed in the ""921 patent suffers from relatively low real-time and functional fidelity with regard to these other subsystems. This is due in part to the complex architecture and low reliability of two separate computer systems, as well as the utilization of relatively simplistic software logic.
In order to emulate other system functions, for example, the system of the ""921 patent as well as other systems utilize dedicated lines connecting the system to remote computers in order to effectuate the transfer of command and telemetry data about the spacecraft bus and payload. These systems thus require additional hardware systems to effectuate all spacecraft functions, take up a relatively large amount of space, are less reliable and provide relatively low functional fidelity.
It is an object of the present invention to provide a low-cost, reliable system for verifying an embedded processor-based system which emulates the entire spacecraft bus and portions of the ground system and which requires less facility resources (e.g. test equipment) in comparison to previously-implemented hardware-in-the-loop systems.
It is a further object of the present invention to provide a system for testing an embedded processor-based system which does not require special purpose interface hardware and harnessing to integrate the embedded processor-based system with a high-fidelity, non-linear, real-time dynamic simulator.
It is still another object of the present invention to provide a system for emulating the transfer of telemetry and command data within a spacecraft that provides fidelity that will enable more realistic ground testing.
It is still a further object of the present invention to provide a test facility with greatly reduced size and cost allowing for greatly increased portability and utility.
It is yet another object of the present invention to provide a complete, very integrated, high fidelity simulation system that is provided in a single enclosure.
In accordance with the objects of the present invention, a spacecraft emulation system is provided. The system includes an emulated spacecraft control processor which contains an embedded processor that provides an emulated input/output interface to communicate simulated spacecraft data, wherein the embedded processor processes the simulated data. The system includes a first simulation engine which processes the attitude control system command data from the emulated spacecraft control processor to simulate the attitude control system (ACS) of the spacecraft in real-time. The first simulation engine is operative to produce the simulated attitude sensor data for input to the emulated spacecraft control processor based on the simulated system dynamics. The system also includes a second simulation engine which processes the non-ACS subsystems of the spacecraft in real-time, specifically, thermal, power propulsion and payload subsystems. The second simulation engine is operative to produce the simulated non-ACS telemetry data for input to the emulated spacecraft control processor and/or ground segment based on the simulated system dynamics. The second simulation engine is in communication with the embedded processor through a VMEbus connection. Additionally, the system includes an emulated central telemetry and command unit (ECTCU) which processes and distributes telemetry and command data. The system includes an interface manager which provides a conduit for command and telemetry data transferred between the ground control system and the ECTCU.